Lou is correct. To change the CW weight parameters for DX'ing and ragchewing I use a Logikey K-5 connected to the Accessory Connector on the back of the Flex. For contesting I plug the paddle directly into the key jack on the front of the flex so the keying speed selected in the N1MM+ software is the same on the paddle.

Wondering if maybe the first step could be to just enable the Flex API so 3rd party programs can tweak the Winkeyer settings?

For example, the N3FJP (ACLog) CW Setup Form has a Winkeyer keying option which can be connected to a SmartSDR CAT Winkeyer. CW weight and other details are controlled in the N3FJP Winkey setup GUI, so if the Flex API accepted those parameters we would be in business.